Maintaining a sterile medical environment is of utmost importance in the field of dentistry and oral surgery. This is to avoid not only the usual infection problem associated with an unsterile environment, but to avoid the potentially more serious problem of cross contamination from patient to patient. The appliance most intimate with the body and therefore the most apt to carry contamination to the patient is the dental handpiece and the working tool carried by it. Typical is the high speed rotary tool which is turbine driven and offers considerable time savings over the earlier types. This includes tools used in procedures such as drilling, cutting and cleaning. However, due to the frictional heat build-up and disintregation, a coolant or irrigant liquid is needed. Historically this is water provided by a building system. Water delivered to the tip of the appliance is not sterile. In addition, the tubing carrying the water cannot be sterilized. Upon turning the handpiece off, water can migrate back into the appliance and into the tubing. There it may harbor and nurture certain bacteria which will pass from one patient to the next.
This problem is addressed and virtually eliminated by the device shown and described in U.S. Pat. No. 4,470,812 issued Sept. 11, 1984 to Martens and Varnes. The device of that patent employs a cartridge carrying a sterile coolant. The cartridge has a flexible diaphram movable internally from one side to the other and dividing the cartridge into two chambers. Initially the chamber carrying the sterile coolant fills the cartridge. Water from the community water supply is introduced into the opposite chamber. As it is introduced into the one chamber, it forces the coolant out of the other through an outlet and through the dental handpiece to the oral cavity. A new cartridge is used for each patient. This results in only sterile coolant at proper temperature being introduced to the oral cavity for purposes of cooling the cutting handpiece and irrigating the surgical site, facilitating the removal of debris generated during the cutting procedure. The device of that patent is dependent upon the existence of a community water supply in order to provide water under pressure to displace the sterile solution in the cartridge for delivery to the oral cavity.